Seasonal variation of serum 25-hydroxyvitamin D level in hemodialysis patients in the northernmost island of Japan.

Background: Serum vitamin D level shows a seasonal variation, being lower in winter than in summer in healthy subjects. The aim of this study was to determine whether there is presence of such a seasonal variation in hemodialysis patients.

Methods: A total of 102 patients on hemodialysis were enrolled in February 2017 (winter) for analyses of serum levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)D] and treatments for chronic kidney disease-mineral and bone disorder (CKD-MBD).

Tyrokeradines C-F, new bromotyrosine alkaloids from the Verongid sponges.

Four new bromotyrosine alkaloids, tyrokeradines C-F (1-4), have been isolated from Okinawan marine sponges of the order Verongidae. The structures of 1-4 were elucidated on the basis of spectroscopic data. Tyrokeradines C (1) and D (2) are new bromotyrosine alkaloids possesing an imidazole ring, while tyrokeradines E (3) and F (4) are new bromotyrosine alkaloids possesing a cyano group.

Tyrokeradines A and B, new bromotyrosine alkaloids with an imidazolyl-quinolinone moiety from a verongid sponge.

Two new bromotyrosine alkaloids, tyrokeradines A (1) and B (2), with an imidazolyl-quinolinone moiety have been isolated from an Okinawan marine sponge of the order Verongida. The structures of 1 and 2 were elucidated on the basis of spectroscopic data.